drm/i915/selftests: Compare user mmap against GPU

Check that the user writes into their mmap are visible on the GPU.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Abdiel Janulgue <abdiel.janulgue@linux.intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Acked-by: Abdiel Janulgue <abdiel.janulgue@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200103204137.2131004-3-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c

@@ -952,6 +952,134 @@ static int igt_mmap(void *arg)
 	return 0;
 }
 
+static int __igt_mmap_gpu(struct drm_i915_private *i915,
+			  struct drm_i915_gem_object *obj,
+			  enum i915_mmap_type type)
+{
+	struct intel_engine_cs *engine;
+	struct i915_mmap_offset *mmo;
+	u32 __user *ux, bbe;
+	unsigned long addr;
+	int err;
+
+	/*
+	 * Verify that the mmap access into the backing store aligns with
+	 * that of the GPU, i.e. that mmap is indeed writing into the same
+	 * page as being read by the GPU.
+	 */
+
+	if (!can_mmap(obj, type))
+		return 0;
+
+	err = wc_set(obj);
+	if (err == -ENXIO)
+		err = gtt_set(obj);
+	if (err)
+		return err;
+
+	mmo = mmap_offset_attach(obj, type, NULL);
+	if (IS_ERR(mmo))
+		return PTR_ERR(mmo);
+
+	addr = igt_mmap_node(i915, &mmo->vma_node, 0, PROT_WRITE, MAP_SHARED);
+	if (IS_ERR_VALUE(addr))
+		return addr;
+
+	ux = u64_to_user_ptr((u64)addr);
+	bbe = MI_BATCH_BUFFER_END;
+	if (put_user(bbe, ux)) {
+		pr_err("%s: Unable to write to mmap\n", obj->mm.region->name);
+		err = -EFAULT;
+		goto out_unmap;
+	}
+
+	if (type == I915_MMAP_TYPE_GTT)
+		intel_gt_flush_ggtt_writes(&i915->gt);
+
+	for_each_uabi_engine(engine, i915) {
+		struct i915_request *rq;
+		struct i915_vma *vma;
+
+		vma = i915_vma_instance(obj, engine->kernel_context->vm, NULL);
+		if (IS_ERR(vma)) {
+			err = PTR_ERR(vma);
+			goto out_unmap;
+		}
+
+		err = i915_vma_pin(vma, 0, 0, PIN_USER);
+		if (err)
+			goto out_unmap;
+
+		rq = i915_request_create(engine->kernel_context);
+		if (IS_ERR(rq)) {
+			err = PTR_ERR(rq);
+			goto out_unpin;
+		}
+
+		i915_vma_lock(vma);
+		err = i915_request_await_object(rq, vma->obj, false);
+		if (err == 0)
+			err = i915_vma_move_to_active(vma, rq, 0);
+		i915_vma_unlock(vma);
+
+		err = engine->emit_bb_start(rq, vma->node.start, 0, 0);
+		i915_request_get(rq);
+		i915_request_add(rq);
+
+		if (i915_request_wait(rq, 0, HZ / 5) < 0) {
+			struct drm_printer p =
+				drm_info_printer(engine->i915->drm.dev);
+
+			pr_err("%s(%s, %s): Failed to execute batch\n",
+			       __func__, engine->name, obj->mm.region->name);
+			intel_engine_dump(engine, &p,
+					  "%s\n", engine->name);
+
+			intel_gt_set_wedged(engine->gt);
+			err = -EIO;
+		}
+		i915_request_put(rq);
+
+out_unpin:
+		i915_vma_unpin(vma);
+		if (err)
+			goto out_unmap;
+	}
+
+out_unmap:
+	vm_munmap(addr, obj->base.size);
+	return err;
+}
+
+static int igt_mmap_gpu(void *arg)
+{
+	struct drm_i915_private *i915 = arg;
+	struct intel_memory_region *mr;
+	enum intel_region_id id;
+
+	for_each_memory_region(mr, i915, id) {
+		struct drm_i915_gem_object *obj;
+		int err;
+
+		obj = i915_gem_object_create_region(mr, PAGE_SIZE, 0);
+		if (obj == ERR_PTR(-ENODEV))
+			continue;
+
+		if (IS_ERR(obj))
+			return PTR_ERR(obj);
+
+		err = __igt_mmap_gpu(i915, obj, I915_MMAP_TYPE_GTT);
+		if (err == 0)
+			err = __igt_mmap_gpu(i915, obj, I915_MMAP_TYPE_WC);
+
+		i915_gem_object_put(obj);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
 static int check_present_pte(pte_t *pte, unsigned long addr, void *data)
 {
 	if (!pte_present(*pte) || pte_none(*pte)) {
@@ -1105,6 +1233,7 @@ int i915_gem_mman_live_selftests(struct drm_i915_private *i915)
 		SUBTEST(igt_mmap_offset_exhaustion),
 		SUBTEST(igt_mmap),
 		SUBTEST(igt_mmap_revoke),
+		SUBTEST(igt_mmap_gpu),
 	};
 
 	return i915_subtests(tests, i915);